This application focuses upon the purification and characterization of the complex of proteins involved in the psychopharmacological actions of the benzodiazepines. Using radioactive ligands, affinity labeling of the benzodiazepine receptor will be carried out. Portions of the active site of the receptor will be removed from the membrane by proteoloysis and purified. Monoclonal antibodies against these fragments will be prepared and used to characterize the benzodiazepine receptor and to isolate the closely linked receptor for gamma aminobutyric acid and the anion channel (picrotoxin sensitive site). By using antibodies linked to a solid matrix, purification of the complex will be carried out; after purification, reconstitution of the purified proteins into artificial membranes will be employed to study kinetic aspects of receptor function. Additional antibodies against the GABA receptor will be prepared and the intrinsic pharmacological activities of these antibodies will be examined. It is expected that by a careful examination of the biochemical parameters of receptor function, greater reliability in predicting the actions of drugs which act at these sites can be made at a preclinical level. Changes (desensitization) in the complex due to chronic benzodiazepine administration or overactivity of GABA will also be studied in the model membrane system. By studying the molecular structure of the GABA-benzodiazepine receptor complex, we expect to gain greater insight into the pharmacology of psychoactive compounds such as diazepam. These compounds are among the most widely prescribed drugs in the world for the treatment of generalized anxiety and our studies may provide insights into the etiology of these conditions.